Methods and apparatus for endovascularly replacing a patient&#39;s heart valve

ABSTRACT

The present invention relates to an apparatus for replacing a native aortic valve, the apparatus includes an expandable anchor adapted to be endovascularly delivered and secured at a site within the native aortic valve. The expandable anchor has a delivery length in a delivery configuration substantially greater than a deployed length in a deployed configuration. The apparatus may also include and a replacement valve configured to be secured within the anchor.

CROSS REFERENCE

This application is a continuation-in-part application of U.S. Ser. No.10/746,280, filed Dec. 23, 2003.

BACKGROUND OF THE INVENTION

Heart valve surgery is used to repair or replace diseased heart valves.Valve surgery is an open-heart procedure conducted under generalanesthesia. An incision is made through the patient's sternum(sternotomy), and the patient's heart is stopped while blood flow isrerouted through a heart-lung bypass machine.

Valve replacement may be indicated when there is a narrowing of thenative heart valve, commonly referred to as stenosis, or when the nativevalve leaks or regurgitates. When replacing the valve, the native valveis excised and replaced with either a biologic or a mechanical valve.Mechanical valves require lifelong anticoagulant medication to preventblood clot formation, and clicking of the valve often may be heardthrough the chest. Biologic tissue valves typically do not require suchmedication. Tissue valves may be obtained from cadavers or may beporcine or bovine, and are commonly attached to synthetic rings that aresecured to the patient's heart.

Valve replacement surgery is a highly invasive operation withsignificant concomitant risk. Risks include bleeding, infection, stroke,heart attack, arrhythmia, renal failure, adverse reactions to theanesthesia medications, as well as sudden death. Two to five percent ofpatients die during surgery.

Post-surgery, patients temporarily may be confused due to emboli andother factors associated with the heart-lung machine. The first 2-3 daysfollowing surgery are spent in an intensive care unit where heartfunctions can be closely monitored. The average hospital stay is between1 to 2 weeks, with several more weeks to months required for completerecovery.

In recent years, advancements in minimally invasive surgery andinterventional cardiology have encouraged some investigators to pursuepercutaneous replacement of the aortic heart valve. See, e.g., U.S. Pat.No. 6,168,614. In many of these procedures, the replacement valve isdeployed across the native diseased valve to permanently hold the valveopen, thereby alleviating a need to excise the native valve and toposition the replacement valve in place of the native valve.

In the endovascular aortic valve replacement procedure, accurateplacement of aortic valves relative to coronary ostia and the mitralvalve is critical. Some self-expanding valve anchors have had very pooraccuracy in deployment, however. In a typical deployment procedure, theproximal end of the stent is not released from the delivery system untilaccurate placement is verified by fluoroscopy. The stent often jumps toanother position once released, making it impossible to know where theends of the stent will be after release with respect to the nativevalve, the coronary ostia and the mitral valve.

Also, visualization of the way the new valve is functioning prior tofinal deployment is very desirable. Due to the jumping action of someself-expanding anchors, and because the replacement valve is often notfully functional before final deployment, visualization of valvefunction and position prior to final and irreversible deployment isoften impossible with these systems.

Another drawback of prior art self-expanding replacement heart valvesystems is their relative lack of radial strength. In order forself-expanding systems to be easily delivered through a delivery sheath,the metal needs to flex and bend inside the delivery catheter withoutbeing plastically deformed. Expandable stent designs suitable forendovascular delivery for other purposes may not have sufficient radialstrength to serve as replacement heart valve anchors. For example, thereare many commercial arterial stent systems that apply adequate radialforce against the artery wall to treat atherosclerosis and that cancollapse to a small enough of a diameter to fit inside a deliverycatheter without plastically deforming. However when the stent has avalve fastened inside it, and that valve must reside within the heart,as is the case in aortic valve replacement, the anchoring of the stentto vessel walls takes significantly more radial force, especially duringdiastole. The force to hold back arterial pressure and prevent bloodfrom going back inside the ventricle during diastole will be directlytransferred to the stent/vessel wall interface. Therefore, the amount ofradial force required to keep the self-expanding stent/valve in contactwith the vessel wall and not sliding is much higher than in stents thatdo not have valves inside of them. Moreover, a self-expanding stentwithout sufficient radial force will end up dilating and contractingwith each heartbeat, thereby distorting the valve, affecting itsfunction and possibly causing it to migrate and dislodge completely.Simply increasing strut thickness of the self-expanding stent is not agood solution as it increases profile and/or a risk of plasticdeformation of the self-expanding stent.

In view of drawbacks associated with previously known techniques forendovascularly replacing a heart valve, it would be desirable to providemethods and apparatus that overcome those drawbacks.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for replacing a nativeaortic valve, the apparatus includes an expandable anchor adapted to beendovascularly delivered and secured at a site within the native aorticvalve. The expandable anchor has a delivery length in a deliveryconfiguration substantially greater than a deployed length in a deployedconfiguration. The apparatus may also include and a replacement valveconfigured to be secured within the anchor.

In some embodiments, the delivery length is between about 15 mm andabout 150 mm and the deployed length is between about 5 mm and about 40mm. In some embodiments, the apparatus has a ratio of delivery length todeployed length that is between about 0.05 and about 0.5; between about0.1 and about 0.35; or between about 0.15 and about 0.25. In someembodiments, the apparatus herein includes an anchor that has an at-restconfiguration and wherein the anchor includes a shape memory materialthat is heat set in the at-rest configuration. The at-rest configurationmay have a length between the delivery length and the deployed length.

In some embodiments, the apparatus herein has an anchor that isconfigured for active foreshortening during endovascular deployment. Theapparatus may also include a lock or a plurality of locks configured tomaintain expansion of the anchor. The lock(s) may also be configured tomaintain expansion of the anchor at a plurality of amounts of expansion,thereby conferring non cylindrical shapes to the apparatus.

In any of the embodiments herein, the apparatus may further include avalve support adapted to support the replacement valve within theanchor. The valve support may also include a lock that is an extensionof the valve support.

In any of the embodiments herein, the apparatus may include a distaldeployment system interface disposed at a distal end of the anchor, thedistal deployment system interface being adapted to permit a deploymentsystem to apply a proximally directed force on the distal end of theanchor. The distal deployment system interface may further be adapted toexpand radially during application of a proximally directed force on thedistal end of the anchor. The distal deployment system interface mayfurther be adapted to permit a deployment system to apply a proximallydirected force on the distal end of the anchor without passing anyportion of a deployment system through a center opening of thereplacement valve.

In some embodiments, the apparatus herein may include an anchor, whereinthe anchor includes a proximal deployment system interface at a proximalend of the anchor, the proximal deployment system interface beingadapted to permit a deployment system to apply a distally directed forceon the proximal end of the anchor. The proximal deployment systeminterface may further be adapted to expand radially during applicationof a distally directed force on the proximal end of the anchor. Theproximal deployment system interface may further be adapted to permit adeployment system to apply a distally directed force on the proximal endof the anchor through a plurality of deployment system fingers.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1A and 1B are schematic top views of an anchor and valve apparatusin accordance with the present invention. FIG. 1 illustrates theapparatus in a collapsed delivery configuration within a deliverysystem. FIG. 1B illustrates the apparatus in an expanded configurationpartially deployed from the delivery system.

FIGS. 2A-2F are schematic isometric views detailing an anchor of theapparatus of FIG. 1 in the collapsed delivery configuration and theexpanded deployed configuration, as well as the full apparatus in thedeployed configuration.

FIG. 3 is a schematic top view of an apparatus for fabricating braidedanchors in accordance with the present invention.

FIGS. 4A-4D are schematic top views illustrating a method of using theapparatus of FIG. 3 to fabricate a braided anchor of the presentinvention.

FIGS. 5A-5O are schematic detail views illustrating features of braidcells at an anchor edge.

FIGS. 6A-6E illustrate further features of braid cells at an anchoredge.

FIGS. 7A-7J are schematic detail views terminations for one or more wirestrands forming anchors of the present invention.

FIGS. 8A and 8B are schematic side views of alternative embodiments ofthe anchor portion of the apparatus of the present invention.

FIGS. 9A-9E are schematic side views of further alternative embodimentsof the of the anchor portion of the apparatus of the present invention.

FIGS. 10A-10D are schematic views of different weave configurations.

FIGS. 11A-11E are schematic side views of various braided anchorconfigurations.

FIGS. 12A-12E are schematic side views of a deployment process.

FIGS. 13A and 13B illustrate a braided anchor in the heart.

FIGS. 14A and 14B illustrate a bilaterally symmetrical anchor and anasymmetric anchor, respectively.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a delivery system, apparatus andmethods for endovascularly delivering and deploying an aortic prosthesiswithin a patient's native heart valve, referred to here out as replacinga patients heart valve. The delivery system includes a sheath assemblyand a guide wire for placing the apparatus endovascularly within apatient and a user control allowing manipulation of the aorticprosthesis. The apparatus includes an anchor and a replacement valve.The anchor includes an expandable braid. In preferred embodiments, theexpandable braid includes closed edges. The replacement valve is adaptedto be secured within the anchor, and as such, be deliveredendovascularly to patient's heart to replace the patient's native heartvalve. More preferably, the apparatus and methods of the presentinvention contemplate the replacement of a patient's aortic valve.

FIGS. 1A and 1B illustrate one embodiment of a delivery system andapparatus in accordance with the present invention is described. Asillustrated by FIG. 1A, apparatus 10 may be collapsed for deliverywithin a delivery system 100. Delivery system 100 includes a guidewire102, a nosecone 104, control tubes 106 coupled to a multi-lumen shaft108, an external sheath 110 having a proximal handle 111, and a controlhandle 120. Delivery system 100 further comprises distal region controlwires (not shown), which pass through one or more lumens of shaft 108and are reversibly coupled to posts 32 of anchor 30 for manipulating adistal region of apparatus 10. The delivery system also comprisesproximal region control wires 112 that pass through one or more lumensof shaft 108 and control tubes 106 (also known as fingers) to reversiblycouple the control tubes to a proximal region of anchor 30. The controlwires may comprise, for example, strands of suture, or metal or polymerwires.

Control handle 120 is coupled to multi-lumen shaft 108. A knob 122disposed in slot 123 is coupled to the distal region control wires forcontrolling movement of the distal region of apparatus 10. Likewise, aknob 124 disposed in slot 125 is coupled to proximal region controlwires 112 for control of the proximal region of apparatus 10. Handle 120may also have a knob 126 for, e.g., decoupling the proximal and/ordistal region control wires from apparatus 10, or for performing othercontrol functions.

Apparatus 10 has an anchor 30 and a replacement valve 20. Anchor 30preferably comprises a braid. Such braid can have closed ends at eitheror both its ends. Replacement valve 20 is preferably coupled to theanchor along posts 32. Post 32 therefore, may function as valve supportand may be adapted to support the replacement valve within the anchor.In the embodiment shown, there are three posts, corresponding to thevalve's three commissure points. The posts can be attached to braidportion of anchor 30. The posts can be attached to the braid's distalend, as shown in FIG. 2A, central region, or proximal end. Replacementvalve 20 can be composed of a synthetic material and/or may be derivedfrom animal tissue. Replacement valve 20 is preferably configured to besecured within anchor 30.

Anchor 30 has also a plurality of buckles 34 attached to its proximalregion, one for each post 32. Posts 32 and buckles 34 form a two-partlocking mechanism for maintaining anchor 30 in a deployed or expandedconfiguration (e.g., as illustrated in FIGS. 1B, 2B and 2C).

In this embodiment, anchor 30 is formed from collapsible and expandablewire braid. Anchor braid 30 is preferably self-expanding and ispreferably formed from a material such as Nitinol, cobalt-chromium steelor stainless steel wire using one or more strands of wire. While theillustrated embodiment is formed from a single strand of wire, in otherembodiments may benefit from a wire braid formed of 2-20 wires, morepreferably 3-15 wires, or more preferably 4-10 wires.

Delivery and deployment of braided anchor 30 is similar to the deliveryand deployment of the anchors described in U.S. patent application Ser.No. 10/746,280 filed Dec. 23, 2003, the disclosure of which isincorporated herein by reference. Specifically, in one embodimentdescribed below, during deployment braided anchor 30 is activelyforeshortened by proximally retracting the distal region control wiresrelative to control tubes 106 to expand and lock the anchor in place. Insome embodiments, foreshortening expands anchor 30 to a radiallysymmetrical, bilaterally symmetrical, or asymmetrical expanded shape (asfurther described below). The foreshortening step can include expandinga first region of the anchor to a first diameter and a second region ofthe anchor to a second diameter larger than the first diameter. A thirdregion may also be expanded to a diameter larger than the firstdiameter. The expansion of various regions of the anchor (e.g., thedistal region) can be especially useful in locating the aortic valve andcentering the anchor within it. Preferably, the secured anchor does notinterfere with the mitral valve or the ostias. In some embodiments, theanchor is allowed to self expand prior to the foreshortening step.

As seen in FIGS. 1, after endovascular delivery through sheath 110 tothe vicinity of the patient's native valve (such as the aortic valve),apparatus 10 may be expanded from the collapsed delivery configurationof FIG. 1A to the expanded deployed configuration of FIG. 1B usingdelivery system 100. To deploy apparatus 10, external sheath 110 may beretracted relative to apparatus 10 by proximally retracting sheathhandle 111 relative to control handle 120. Sheath 110 is thereby removedfrom the exterior of apparatus 10, permitting the anchor 30 toself-expand. In preferred embodiments, anchor 30 includes sheathingfeatures as depicted in FIGS. 5B thru 5M or FIGS. 6, 7A, or 7D adaptedto reduce sheathing force. Sheathing force is defined as the forcerequired to push the sheath distally over the anchor or the forcerequired to pull the anchor proximally into the sheath (as for purposesof retrieving the anchor). For example, if anchor braid 30 is composedof a shape memory material, it may self-expand to or toward its“at-rest” configuration. This “at rest” configuration of the braid canbe, for example its expanded configuration, a collapsed configuration,or a partially expanded configuration between the collapsedconfiguration and the expanded configuration. In preferred embodiments,the anchor's at-rest configuration is between the collapsedconfiguration and the expanded configuration. Depending on the “at rest”diameter of the braid and the diameter of the patient's anatomy at thechosen deployment location, the anchor may or may not self-expand tocome into contact with the diameter of the patient's anatomy at thatlocation.

In its collapsed configuration, anchor 30 preferably has a collapseddelivery diameter between about 3 to 30 Fr, or more preferably 6 to 28Fr, or more preferably 12 to 24 Fr. In some embodiments, anchor 30 inits collapsed configuration will have a length ranging from about 5 toabout 170, more preferably from about 10 to about 160, more preferablyfrom about 15 to about 150, more preferably from about 20 to about 140mm, or more preferably from about 25 mm to about 130.

Similarly, in its expanded configuration, anchor 30 preferable has adiameter ranging between about 10 to about 36 mm, or more preferablyfrom about 24 to about 33 mm, or more preferably from about 24 to about30 mm. In some embodiments, anchor 30 in its expanded configuration willhave a length ranging from about 1 to about 50, more preferably fromabout 2 to about 40, more preferably from about 5 to about 30, or morepreferably from about 7 to about 20 mm.

Overall, the ratio of deployed to collapsed/sheathed lengths ispreferably between about 0.05 and 0.5, more preferably about 0.1 to0.35, or more preferably about 0.15 to 0.25. In any of the embodimentsherein, anchor 30 in its expanded configuration preferably has a radialcrush strength that maintains the anchor substantially undeformed inresponse to a pressure of up to 0.5 atm directed substantially radiallyinward toward the central axis, or more preferably up to 2 atm directedsubstantially radially inward toward the central axis. In addition, inany of the embodiments herein, the anchor has an axial spring constantof between about 10 to 250 g/cm, more preferably between about 20 to 200g/cm, or more preferably between about 40 to 160 g/cm. In addition, inany of the embodiments herein, the anchor is preferably adapted tosupport the replacement valve at the anchor site in response to adifferential pressure of up to 120 mm Hg, more preferably up to 240 mmHg, or more preferably up to 320 mm Hg.

These parameters are not intended to be limiting. Additional parameterswithin the scope of the present invention will be apparent to those ofskill in the art.

As seen in FIG. 1B, anchor 30 may be expanded to a fully deployedconfiguration from a partial deployed configuration (e.g., self-expandedconfiguration) by actively foreshortening anchor 30 during endovasculardeployment. As described in more detail in U.S. patent application Ser.No. 10/746,280, the distal region of anchor 30 may be pulled proximallyvia a proximally directed force applied to posts 32 via a distaldeployment system interface. The distal deployment system interface isadapted to expand radially during application of a proximally directedforce on the distal end of the anchor. In some embodiments,foreshortening of the apparatus involves applying a proximally directedforce on a deployment system interface at the distal end of the anchor.In other embodiments, foreshortening of the apparatus involves applyinga distally directed force on a deployment system interface at theproximal end of the anchor. More preferably, proximally or distallydirected forces on the deployment system interface do not diametricallyconstrain the opposite end of the anchor—distal or proximal end,respectively. When a proximally directed force is applied on thedeployment system interface, it is preferably applied without passingany portion of a deployment system through a center opening of thereplacement valve.

The distal deployment system interface may include control wires thatare controlled, e.g., by control knob 122 of control handle 120.Similarly, the proximal regions of anchor 30 may be pushed distally viaa proximal deployment system interface at the proximal end of theanchor. The proximal deployment system interface is adapted to permitdeployment system to apply a distally directed force to the proximal endof anchor 30 through, e.g., fingers 106, which are controlled by, e.g.,Control knob 124 of control handle 120. The proximal deployment systeminterface may be further adapted to expand radially during applicationof a distally directed force on the proximal end of the anchor.Preferably, the proximal deployment system interface is adapted topermit deployment system to apply a distally directed force on theproximal end of the anchor system through a plurality of deploymentsystem fingers or tubes 160. Such expansion optionally may be assistedvia inflation of a balloon catheter (not shown) reversibly disposedwithin apparatus 10, as described in U.S. patent application Ser. No.10/746,280.

Once anchor 30 is fully deployed, posts 32 and buckles 34 of anchor 30may be used to lock and maintain the anchor in the deployedconfiguration. In one embodiment, the control wires attached to posts 32are threaded through buckles 34 so that the proximally directed forceexerted on posts 32 by the control wires during deployment pulls theproximal locking end of posts 32 toward and through buckles 34. Suchlock optionally may be selectively reversible to allow for repositioningand/or retrieval of apparatus 10 during or post-deployment. Apparatus 10may be repositioned or retrieved from the patient until the two-partlocking mechanism of posts 32 and buckles 34 of anchor 30 have beenactuated. When the lock is selectively reversible, the apparatus may berepositioned and/or retrieved as desired, e.g., even after actuation ofthe two-part locking mechanism. Once again, further details of this andother anchor locking structures may be found in U.S. patent applicationSer. No. 10/746,280. Locking mechanisms used herein may also include aplurality of levels of locking wherein each level of locking results ina different amount of expansion. For example, the proximal end of thepost can have multiple configurations for locking within the bucklewherein each configuration results in a different amount of anchorexpansion.

When apparatus 10 is placed across a patient's diseased heart valve,anchor 30 may be used to displace the patient's native valve leaflets,and replacement valve 20 will thereafter serve in place of the nativevalve. After final positioning and expansion, apparatus 10 may bedecoupled from delivery system 100 by decoupling the proximal and distalregion control wires from anchor 30. Decoupling may be actuated usingknob 126 of handle 120. After decoupling, delivery system 100 then maybe removed from the patient, thereby completing endovascular replacementof a patient's heart valve.

Prior to implantation of replacement valve apparatus described herein,it may be desirable to perform a valvuloplasty on the patient's diseasedvalve by inserting a balloon into the valve and expanding it using,e.g., saline mixed with a contrast agent. In addition to preparing thevalve site for implant, fluoroscopic viewing of the valvuloplasty willhelp determine the appropriate size of replacement valve implant to use.

FIGS. 2A-F show further details of anchor 30 of apparatus 10. FIG. 2Ashows the apparatus in a collapsed configuration, such as for deliverywithin a sheath or other lumen or for retrieval and recapture into asheath or other lumen. FIGS. 2B and 2C show the anchor and valve in anexpanded and locked configuration.

As shown in FIG. 2C, anchor 30 has three posts and three buckles. Asseen in FIG. 2C, the three leaflets of replacement valve 20 may becoupled to the three posts 32 also known as valve supports. The posts,unlike the braid, do not collapse or expand. In some embodiments a post32 has one or more proximal slots 33, at least one proximal hole 36 aand at least one distal hole 36 b. Leaflet tissue may be passed throughslot 33 and sutured in place via suture routed through one or moreproximal holes 36 a. Other means known in the art for fixing valveleaflets to posts may also be employed.

Posts 32 may be coupled to anchor braid 30 via one dr more distal holes36 b. For example, anchor braid 30 may be woven through holes 36 b, or asuture may be routed through holes 36 b and tied to the braid. Buckles34 may likewise be attached to anchor braid 30 via weaving or suturing.

Alternative locks may be used to lock the anchor of the presentinvention in the foreshortened configuration. Preferably, a lockingmechanism of the present invention can have multiple locking optionssuch that locking can confer a plurality of amounts of expansion.Furthermore, the locking option can be employed asymmetrically to confernon-cylindrical shapes to the anchor. In FIG. 2D, lock 40′ comprisesmale interlocking element 44 as described previously. However, femaleinterlocking element 42′ illustratively comprises a triangular shape, ascompared to the round shape of interlocking element 42 describedpreviously. The triangular shape of female interlocking element 42′ mayfacilitate mating of male interlocking element 44 with the femaleinterlocking element without necessitating deformation of the maleinterlocking element.

In FIG. 2E, lock 40″ comprises alternative male interlocking element 44′having multiple in-line arrowheads 46 along posts 32. Each arrowheadcomprises resiliently deformable appendages 48 to facilitate passagethrough female interlocking element 42. Appendages 48 optionallycomprise eyelets 49, such that control wire 50 or a secondary wire maypass therethrough to constrain the appendages in the deformedconfiguration. To actuate lock 40″, one or more arrowheads 46 of maleinterlocking element 44′ are drawn through female interlocking element42, and the wire is removed from eyelets 49, thereby causing appendages48 to resiliently expand and actuate lock 40″.

Advantageously, providing multiple arrowheads 46 along posts 32 yields aratchet that facilitates in-vivo determination of a degree offoreshortening imposed upon apparatus of the present invention.Furthermore, optionally constraining appendages 48 of arrowheads 46 viaeyelets 49 prevents actuation of lock 40″ (and thus deployment ofapparatus of the present invention) even after male element 44′ has beenadvanced through female element 42. Only after a medical practitionerhas removed the wire constraining appendages 48 is lock 40″ fullyengaged and deployment no longer reversible.

Lock 40′″ of FIG. 11C is similar to lock 40″ of FIG. 2E, except thatoptional eyelets 49 on appendages 48 have been replaced by optionalovertube 47. Overtube 47 serves a similar function to eyelets 49 byconstraining appendages 48 to prevent locking until a medicalpractitioner has determined that apparatus of the present invention hasbeen foreshortened and positioned adequately at a treatment site.Overtube 47 is then removed, which causes the appendages to resilientlyexpand, thereby fully actuating lock 40″″.

FIG. 3 illustrates an exemplary apparatus for fabricating braidedanchors. Such apparatus includes a cylindrical braiding fixture 200. Thecylindrical braiding fixture 200 comprises proximal circumference ofinner posts 202 a separated by a distance x from distal circumference ofinner posts 202 b. x can be, for example, 10 to 60 mm, more preferably20 to 50 mm, or more preferably 30 to 40 mm. Optionally, the fixture mayalso comprise proximal and distal circumferences of outer posts 204 aand 204 b, respectively. 204 a and 204 b can be situated about 2-10 mmfrom 202 a and 202 b, respectively. Posts 202 a/b and 204 a/b projectfrom fixture 200 and may be used to route wire, e.g., for forming anchorbraid 30. Inner posts 202 a and 202 b generally facilitate formation ofa braid, while outer posts 204 a and 204 b generally facilitateformation of desired features at the ends of the braid, as describedhereinafter with respect to FIGS. 5-8.

In some embodiments, fixture 200 comprises approximately 6-20 posts,more preferably 8-18 posts, or more preferably 10-16 posts around itscircumference, though any alternative number of posts may be provided.Likewise, fixture 200 preferably has a diameter of about 2-40 mm, morepreferably 4-30 mm, or more preferably 6-20 mm, though any alternativediameter may be provided. The diameter of fixture 200 preferably is thediameter of the braid in its “at rest” configuration.

Fixture 200 can optionally further comprise circumferential grooves 206to facilitate interweaving of a first section of wire underneath anadjacent section of wire. The fixture optionally also may compriselocalized depressions or holes 208 in addition, or as an alternative, togrooves 206. Depressions 208 may be provided at locations where wiresegments cross to act as a visual guide for formation of anchor braid30, as well as to facilitate the interweaving of a first section of wirebeneath an adjacent section of wire.

Referring now to FIGS. 4A-D, an illustrative method of using fixture 200to fabricate braided anchors in accordance with the present invention isdescribed. FIG. 4A provides a detail view of a proximal front sideregion of fixture 200 during formation of a braided anchor. FIG. 4Bshows a detail backside view of a central section of the fixture. FIG.4C shows a full-length frontside view of the fixture and FIG. 4D showsthe completed braid. In FIGS. 4, anchor braid 30 is formed from a singlestrand of wrapped and interwoven wire W. However, it should beunderstood that anchor braid 30 alternatively may be formed frommultiple strands of wire.

As seen in FIG. 4A, formation of anchor braid 30 begins with wire Wbeing routed from starting position P near the proximal end of fixture200 past outer proximal posts 204 a and inner proximal posts 202 a. WireW preferably is formed from a superelastic and/or shape-memory material,such as Nitinol. However, alternative wire materials may be utilized,including Cobalt-Chromium, Steel and combinations thereof, as well asadditional materials that will be apparent to those of skill in the art.

After passing inner proximal posts 202 a, wire W encircles fixture 200in a helical spiral while extending towards the distal posts, as seen inFIGS. 4B and 4C. The wire illustratively encircles fixture 200 a full360° revolution plus one additional post. However, any alternativedegree of winding may be provided (e.g., a full 360° plus 2 additionalposts, a full 360° plus 3 additional posts, or a number of posts lessthan a full 360°). As will be apparent to those of skill in the art,altering the degree of winding will alter the expansion characteristicsof the resultant braid in ways per se known.

At distal inner posts 202 b, wire W forms turn Tu and is rerouted backtowards proximal inner posts 202 a. It should be noted that wire W canform turn Tu in either inner posts 202 or outer posts 204. Turn Tu formsa closed end of the braid. Additional sets of inner and outer posts arealso contemplated. The wire once again encircles fixture 200 in a full360° helical revolution plus one additional post before reaching theproximal inner posts and being rerouted back towards the distal innerposts. This process is repeated with the wire repetitively interwoven atcrossing locations between the proximal and distal posts, e.g., viagrooves 206 and/or depressions 208, to define the cells of the braidthat will provide anchor 30 with desired characteristics. As seen inFIG. 4D, wire W turns both proximally and distally in order to completeformation of the braid. In this embodiment, wire W terminates in thecentral portion of the braid at T. Termination T may be formed, forexample, by welding the wires together, applying a shrink tube about theoverlap, using a crimp, braising the wires, etc. Additional techniqueswill be apparent to those of skill in the art.

When anchor braid 30 is formed from a shape-memory material, the braidmay be heat set such that it maintains a desired degree of expansion inan at-rest configuration. The heat set at-rest configuration maycomprise, for example, the delivery configuration (e.g., collapsedconfiguration) of FIG. 2A, the deployed configuration (e.g., expandedconfiguration) of FIGS. 2B and 2C, or any desired configurationtherebetween. In preferred embodiments, the anchor is heat-set in aconfiguration between the delivery configuration and the deployedconfiguration. Anchor braid 30 may be heat set while still disposed onfixture 200 to maintain an at-rest configuration as formed on thefixture, which preferably is a configuration between the delivery anddeployed configurations. Alternatively, the braid may be heat set aftercomplete or partial removal from the fixture. As yet anotheralternative, the braid may be initially heat set while still disposed onthe fixture, but thereafter may be additionally heat set in a differentshape, for example, a more expanded configuration. It is expected thatheat setting anchor braid 30 will provide the braid with desireddelivery and/or deployment characteristics.

Referring now to FIGS. 5A-5O, in conjunction with FIGS. 2C and 4, ananchor braid 30 may be defined by a set of cells that is different thanother cells. Such cells may be formed to provide anchor braid 30 withone or more edge features (for either or both the distal and proximalends). These edge features can, for example, reduce or relieve stresswithin the braid during delivery and deployment, which in turn mayreduce the incidence of anchor material fatigue caused by the pulsatileanchor motion of the anchor site. As will be apparent to those of skillin the art, forming braid 31 from a single strand of wire W (or frommultiple strands of wire W that form turns or that are joined together)may lead to stress concentration at turns Tu in the wire where the wirechanges direction and extends back towards the opposite end of thebraid. Such stress concentration may be most pronounced while the braidis disposed in its extreme configurations, i.e. when the braid isdisposed in the collapsed delivery configuration of FIG. 2A or theexpanded deployed configuration of FIGS. 2B and 2C.

Stress concentration may increase the rigidity of an anchor braid and/ormay impede delivery and deployment, as well as sheathing, of the braid.Thus, in preferred embodiments, a group of cells can be configured toreduce the sheathing force as described herein. Furthermore, to enhancedeliverability, stress concentration may require that anchor braid 30 befabricated from a relatively thin wire W. However, thin wire may notprovide anchor braid 30 with adequate radial strength to displace apatient's diseased native heart valve leaflets and/or to anchorapparatus 10 against a patient's anatomy. Conversely, use of arelatively thick wire W may increase stiffness, thereby precludingretrograde delivery of apparatus 10, as well as a risk of kinking atturns in the braid. Thus, in some embodiments, wires varying inthickness may be used, or multiple wires having different thickness maybe woven together. Also, wires made from different materials may be usedto form an anchor braid.

It may be desirable to reduce stress concentration at the edges ofanchor 30 where wire W changes direction and/or to reduce thecircumferential stiffness of the anchor braid. The edge characteristicsof the anchor may be altered by altering the shape of substantially allanchor braid cells at the anchor's edge (e.g., distal edge and/orproximal edge). Wire turns that control the shape of the edge cells maybe formed within anchor braid 30 by routing wire W around optional outerposts 204 of fixture 200 during formation of the braid. FIG. 5Aillustrates a detail view of a standard end turn Tu in an anchor braidresulting in a braid with substantially uniform cell size and shape.FIG. 5B illustrates a turn that has been elongated to lengthen thedistance over which forces concentrated in the turn may be distributed,resulting in an anchor braid having edge cells that are longer along theanchor axis than the other cells defined by the braid. This elongatedturn feature may be formed by routing the wire of braid about outerposts 204 of fixture 200, and then heat setting the wire.

FIG. 5C illustrates an alternative anchor edge cell configuration,wherein the tip of the elongated wire turn has been bent out of acylindrical shape defined by the braid of anchor braid 30. This may beachieved, for example, via a combination of routing of wire W withinfixture 200 and heat setting. The out-of-plane bend of turn Tu in theanchor edge cells in FIG. 5C may reduce stress in some configurations,and may also provide a lip for engaging the patient's native valveleaflets to facilitate proper positioning of apparatus 10 duringdeployment.

In FIG. 5D, a W-shaped turn feature has been formed at the wire turn,e.g., by routing the wire of anchor braid 30 about a central inner post202 and two flanking outer posts 204 of fixture 200. As with theelongated braid cells of FIGS. 5B and 5C, the W-shape may betterdistribute stress about turn Tu. The anchor edge cell configuration inFIG. 5E includes a loop formed in braid 31 at the turn, which may beformed by looping wire W around an inner or outer post of fixture 200.FIG. 5F provides another alternative anchor edge cell configurationhaving a figure-eight shape. Such a shape may be formed, for example, bywrapping wire W about an inner post 202 and an aligned outer post 204 ina figure-eight fashion, and then heat setting the wire in the resultantshape.

In FIG. 5G, the edge cells of braid 31 include a heart-shapedconfiguration, which may be formed by wrapping the wire about an alignedinner and outer post of fixture 200 in the desired manner. In FIG. 5H,the edge cells of braid 31 have an asymmetric loop at turn Tu. Theasymmetric loop will affect twisting of braid 31 during expansion andcollapse of the braid, in addition to affecting stress concentration. InFIG. 5I, the anchor edge cells have a double-looped turn configuration,e.g. via wrapping about two adjacent inner or outer posts of fixture200. Additional loops may also be employed. The double loop turn featuremay be formed with a smooth transition between the loops, as in FIG. 5I,or may be heat set with a more discontinuous shape, as in FIG. 5J.

FIG. 5K illustrates that the edge cells of braid 31 may have multipledifferent configurations about the anchor's circumference. For example,the anchor edge cells shown in FIG. 5K have extended length cells as inFIG. 5B disposed adjacent to standard size edge cells, as in FIG. 5A.The anchor edge cells of FIG. 5L have an extended turn configurationhaving an extended loop. The anchor edge cells shown in FIG. 5M have analternative extended configuration with a specified heat set profile.Finally, the anchor edge cells shown in FIG. 5N that overlap or areinterwoven to be coupled to one another.

In preferred embodiments, the edge cells may be wrapped using wire,string, or sutures, at a location where the wire overlaps after an endturn as is illustrated in FIG. 5O. This tied-end turn feature preventscells from interlocking with each other during deployment.

The edge cell configuration of FIG. 5 may be heat set independently ofthe rest of the braid. The anchor edge cell configurations of FIGS. 5are provided only for the sake of illustration and should in no way beconstrued as limiting. Additional turn features within the scope of thepresent invention will apparent to those of skill in the art in view ofFIGS. 5. Furthermore, combinations of any such turn features may beprovided to achieve desired characteristics of anchor braid 30.

Referring now to FIGS. 6A-E, additional configurations for reducingstress concentration and/or circumferential stiffness of anchor braid 30are illustrated. Such configurations can be used independently or inconjunction with other configurations disclosed herein. Suchconfigurations are preferably used at the anchor's edges to locallyreduce the cross-sectional area of substantially all cells or all cellsin the anchor braid's edge (e.g., proximal and/or distal). As seen inFIGS. 6A and 6B, turns Tu in wire W typically may have a substantiallycontinuous (e.g., round) cross-sectional profile. As seen in FIG. 6C,modifying the edge cell configuration by locally reducing the thicknessor cross-sectional area of wire W at turn(s) Tu will reduce stressconcentration within the wire at the turns and facilitate collapseand/or expansion of anchor braid 30 from the delivery to the deployedconfigurations. Furthermore, it is expected that such localizedreduction in thickness or cross-sectional area will reduce a risk ofkinking, fatigue or other failure at turns Tu.

Localized reduction may be achieved via a localized etching and/orelectropolishing process. Alternatively or additionally, localizedgrinding of the turns may be utilized. Additional processing techniqueswill be apparent to those of skill in the art. As seen in FIGS. 6D-6E,wire W may, for example, comprise an oval or rectangular cross-sectionalprofile, respectively, after localized reduction. The wire alternativelymay comprise a round profile of reduced cross-sectional area (notshown). Additional profiles will be apparent. Localized reduction cantake place at any time (e.g., before or after a braid is woven).Preferably, localized reduction occurs after weaving. However, in someembodiments, a wire of a given length may be etched or ground at presetsegments and subsequently woven.

Referring now to FIGS. 7A-J, instead of terminating the beginning andend of wire W of braid 31 at an overlap within the braid, as discussedpreviously, the two ends of the wire may be terminated at the anchor'sedge. Likewise, when braid 31 is fabricated from multiple wires W, thewires (or a subset of the wires) optionally may be joined together orterminated at turn(s) of the braid. In FIG. 7A, wire termination T atthe ends of wire(s) W comprises a hinged termination with hinge post 38.In FIG. 7B termination T comprises a clipped or crimped termination withend cap 39. In FIG. 7C, cap 39 is wrapped about the ends of wire W toform wrapped termination T.

In FIG. 7D, cap 39 is placed over the wire ends, which are then bent toprovide a swivel termination. In FIG. 7E, the wire ends are pottedwithin cap 39 at termination T. In FIG. 7F, cap 39 is swaged about thewire ends. In FIG. 7G, the wire ends are welded or glued together. InFIG. 7G, the wire ends are spot welded together. Alternatively, the wireends may be braised to form termination T, as in FIG. 7H. As yet anotheralternative, cap 39 may be placed about the wire ends, and kinks K maybe formed in wire W to provide the ends of the wire with an‘over-center’ bias that maintains termination T, e.g., swiveltermination T. Additional terminations will be apparent to those ofskill in the art.

With reference now to FIGS. 8A-B, alternative anchors of the presentinvention are described having anchor edge features that facilitatesheathing of the apparatus and reduce the sheathing force. In FIG. 8A,the edge cells of anchor 30 have inwardly canted configurations at thewire turns Tu about a proximal circumference of the anchor. These edgecell configurations provide the proximal circumference with a conicalprofile that facilitates sheathing of the apparatus within a deliverysystem, e.g., previously described delivery system 100, by allowingcollapse of anchor 30 to proceed in a more gradual and/or continuousmanner, and funneling the anchor into the sheath.

FIG. 8B illustrates another alternative anchor 30 having edge cellconfigurations formed by wire turns Tu about its proximal circumferencethat first cant outward, and then cant inward. The inward cant providesthe proximal circumference with a conical profile and may facilitatesheathing, while the outward cant may facilitate anchoring at atreatment site, e.g., may engage a patient's native valve leaflets. Aswill be apparent, the edge cell configurations of FIG. 8, as well asthose of FIGS. 5-7, optionally may be provided at either the proximal ordistal ends of the anchor, or both. The edge cell configurations of FIG.8, as well as those of FIGS. 5 and 7, may, for example, be formed byheat setting braid 31 in the desired configuration.

Referring now to FIG. 9, further alternative anchors are describedhaving edge cell configurations adapted to lock the anchor in thedeployed configuration to maintain expansion. In FIG. 9A, anchor 30comprises elongated, hooked edge cells formed from wire turns Tu thatare configured to snag braid 31 and maintain the anchor in the deployedconfiguration, as shown. In FIG. 9B, the hooked turn features have beenelongated, such that the hooks are configured to snag the opposing endof anchor 30 to maintain expansion.

In FIG. 9C, anchor edge cells defined by wire turns TuP and distal turnfeatures TuD are configured to interlock between the ends of anchorbraid 30 in order to maintain the deployed configuration of anchor 30.The proximal edge cells form a hook adapted to engage elongated turns ofthe distal turn features. As will be apparent, the disposition of all ora portion of the proximal and distal edge cell configurations optionallymay be reversed, i.e. the proximal edge cells may form hooks and thedistal edge cells may be configured as elongated turns. FIG. 9Dillustrates interlocking proximal and distal edge cell configurations ofmore complex geometry. FIG. 9E illustrates interlocking proximal anddistal edge cell configurations while anchor 30 is disposed in thecollapsed delivery configuration. The locking turn features of FIGS. 9may, for example, be formed by heat setting anchor braid 30 (or lockingfeatures only) in the desired configuration. Additional locking turnfeatures will be apparent to those of skill in the art. In preferredembodiments, the anchor locking mechanism can be set to have alternativelocking options that allow for various amounts of expansion.

FIGS. 10A-10D illustrate various embodiments of anchor braids. An anchorbraid can be made of one or more wire and can be used to form variousdensity braids. The density of the braid can be assessed by the size ofcells formed by the weave. In some embodiments, two or more differentdensity braids may be woven together. For example, FIG. 10A illustratestwo groups of cells or two braids interwoven in the center. The topgroup of cells forms a more open weave than the bottom group of cells,which forms a denser weave. FIG. 10B illustrates another embodiment ofan anchor braid having three groups of cells. The top and bottom(proximal and distal) edges of the anchor braid have denser cells thanthe central portion of the anchor. Also, the edges of the anchor arewoven from a thinner filament than the central portion. In anotherembodiment illustrated by FIG. 10C, all three sections of an anchorvalve are woven by more than one wire. The wires of each section aremade of a different material and/or thickness. Wires at the sectionalboundaries may or may not interconnect with wires from a differentsection. Each of the sections of the braid anchor may be composed of adifferent number of wires. FIG. 10D illustrates another embodiment of abraided anchor having three sections. In this embodiment, all sectionsare composed of a single wire. The proximal and distal sections/edges ofthe braided anchor have the same pitch. The central region of thebraided anchor has a different pitch than the edge sections.

FIGS. 11A-11E illustrate side views of braided anchor having more thanone braid pitch. Varying pitch within the anchor allows localizedvariations in foreshortening across the anchor, as greaterforeshortening is achieved by higher pitch of the braid. Moreover, thelocalized foreshortening features allow for the design of a braid whichincorporates various diameters depending upon the amount offoreshortening. (The greater the foreshortening, the greater thediameter increase upon deployment.)

FIG. 11A, for example, is a side view representation of braided anchorof FIG. 10D. On the left side of the figure, the expanded anchor isillustrated having a denser weave (shorter pitch) at the distal andproximal ends; hence the dots are located closer to each other. Themiddle section of the anchor is composed of a looser weave that isgenerated by a higher pitch braid and is represented by dots that arefarther away from each other. On the right side of the figure, thebraided anchor is foreshortened and the dots are collapsed closer toeach other. In this case, the central portion of the anchorforeshortened more than the proximal and distal edges. FIG. 11Billustrates a side view of a foreshortened braided anchor that iscreated by low pitch at the edges and high pitch in the middle. FIG. 11Cillustrates a side view of a foreshortened braided anchor that iscreated by high pitch edges and low pitch middle section. FIG. 11Dillustrates a side view of a foreshortened braided anchor that includesa sealing feature or space filling feature at both ends. This type ofanchor can be created by a high pitch braid at edges, low pitch braid inthe middle and heat setting the edges to curl upon unsheathing. This endfeature is useful in facilitating anchoring by functioning as a locatorand sealing. FIG. 11E illustrates a side view of a foreshortened braidedanchor that is associated with an everting valve or locational features.

In preferred embodiments, the middle section of the anchor may becomposed of thicker wire(s) than edge section(s)

FIGS. 12A-12C illustrate an example of the process of deploying theanchor, such as the one illustrated in FIG. 11B above. FIG. 12Aillustrates a braided anchor 30 in its expanded configuration. Theanchor is composed of three sections. The distal and proximal sectionsof the anchor are made of a fine weave (low pitch) braid. The middlesection of the anchor is made of a higher pitch braid and are preferablyheat set to roll upon unsheathing. Furthermore, in preferredembodiments, the filaments of the distal and proximal sections may bethinner (e.g. 0.005 in thickness) than the filaments of the middlesection (e.g., 0.010 in thickness). Posts 32 are coupled to the middlesection of the anchor. For deployment, tubes 106 are coupled to theanchor's middle section. FIG. 12B illustrates the process of deployment.As the anchor is pushed distally by the tubes and pulled proximally bywires, it is unsheathed and begins foreshortening. The distal sectionrolls up and can act as a locator, assisting the operator in locatingthe aortic valve. It then functions as a seal preventing leakage. Theproximal section may optionally also roll up. In FIG. 12C, the devicemay be configured such that the middle section of the valve may form anhour glass shape or a round shape. The tubes may subsequently be removedas described before. FIG. 12D is another illustration of the braidedanchor in its elongated configuration. FIG. 12E is another illustrationof the braided anchor in its foreshortened configuration.

FIGS. 13A-13B illustrate another embodiment of a braided anchor. In thisembodiment, the anchor includes two sections—a distal section made of afine weave and a higher pitch braid than the proximal section. In FIG.13A the device is deployed such that the distal section made of the fineweave is distal to the aortic valve. In FIG. 13B, the distal section isforeshortened, either by heat set memory or actively. The foreshorteningof the distal section allows the operator to locate the valve andsituate the anchor prior to release.

The anchors described herein can be, for example, radially symmetrical,bilaterally symmetrical, or asymmetrical. A radially symmetrical anchoris one for which symmetry exists across any diameter. A bilaterallysymmetrical anchor is one for which symmetry exists across a finitenumber if diameters). An asymmetrical anchor is one for which thereexists no diameter across which a symmetry may be found. FIG. 2Billustrates one embodiment of a radially symmetrical anchor. FIG. 14Aillustrates one embodiment of a bilaterally symmetrical anchor. FIG. 14Billustrates two embodiments (side and top views) of asymmetricalanchors. The benefits of bilaterally symmetrical an asymmetrical anchorsis their ability to avoid interfering with anatomical features, such as,for example the coronary ostial and/or mitral valve. Thus, in preferredembodiments, a braided anchor includes a region adapted to preventexpansion of the anchor into the mitral valve, as is illustrated in FIG.14A.

While preferred embodiments of the present invention are shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will occur to those skilled inthe art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1. Apparatus for replacing a native aortic valve, the apparatuscomprising: an expandable anchor adapted to be endovascularly deliveredand secured at an anchor site within the native aortic valve, theexpandable anchor having a delivery length in a delivery configurationsubstantially greater than a deployed length in a deployedconfiguration; and a replacement valve configured to be secured withinthe anchor.
 2. The apparatus of claim 1 wherein the delivery length isbetween about 15 mm and about 150 mm and the deployed length is betweenabout 2 mm and about 40 mm.
 3. The apparatus of claim 2 wherein thedelivery length is between about 20 mm and about 140 mm and the deployedlength is between about 5 mm and about 30 mm.
 4. The apparatus of claim2 wherein the delivery length is between about 25 mm and about 130 mmand the deployed length is between about 7 mm and about 20 mm.
 5. Theapparatus of claim 1 wherein ratio of delivery length to deployed lengthis between about 0.05 and about 0.5.
 6. The apparatus of claim 5 whereinratio of delivery length to deployed length is between about 0.1 andabout 0.35.
 7. The apparatus of claim 6 wherein ratio of delivery lengthto deployed length is between about 0.15 and about 0.25.
 8. Theapparatus of claim 1 wherein the anchor has an at-rest configuration andwherein the anchor comprises a shape memory material that is heat set inthe at-rest configuration.
 9. The apparatus of claim 8 wherein theat-rest configuration has a length between the delivery length and thedeployed length.
 10. The apparatus of claim 1 wherein the anchor isconfigured for active foreshortening during endovascular deployment. 11.The apparatus of claim 1 further comprising a lock configured tomaintain expansion of the anchor.
 12. The apparatus of claim 1 furthercomprising a plurality of locks configured to maintain expansion of theanchor.
 13. The apparatus of claim 12 wherein the plurality of locks arefurther configured to maintain expansion of the anchor at a plurality ofamounts of expansion.
 14. The apparatus of claim 1 further comprising avalve support adapted to support the replacement valve within theanchor.
 15. The apparatus of claim 14 further comprising a lockconfigured to maintain expansion of the anchor.
 16. The apparatus ofclaim 15 wherein the lock comprises an extension of the valve support.17. The apparatus of claim 1 wherein the anchor comprises a distaldeployment system interface disposed at a distal end of the anchor, thedistal deployment system interface being adapted to permit a deploymentsystem to apply a proximally directed force on the distal end of theanchor.
 18. The apparatus of claim 17 wherein the distal deploymentsystem interface is further adapted to expand radially duringapplication of a proximally directed force on the distal end of theanchor.
 19. The apparatus of claim 18 wherein the distal deploymentsystem interface is further adapted to permit a deployment system toapply a proximally directed force on the distal end of the anchorwithout passing any portion of a deployment system through a centeropening of the replacement valve.
 20. The apparatus of claim 1 whereinthe anchor comprises a proximal deployment system interface at aproximal end of the anchor, the proximal deployment system interfacebeing adapted to permit a deployment system to apply a distally directedforce on the proximal end of the anchor.
 21. The apparatus of claim 20wherein the proximal deployment system interface is further adapted toexpand radially during application of a distally directed force on theproximal end of the anchor.
 22. The apparatus of claim 20 wherein theproximal deployment system interface is further adapted to permit adeployment system to apply a distally directed force on the proximal endof the anchor through a plurality of deployment system fingers.